(a) Field of the Invention
The present invention relates to a plasma display panel (PDP), and more particularly, to a plasma display panel having a barrier rib structure between two substrates that defines discharge cells into independent units.
(b) Description of the Related Art
A PDP is typically a display device in which ultraviolet rays generated by the discharge of gas excite phosphors to realize predetermined images. As a result of the high resolution possible with PDPs (even with large screen sizes), many believe that they will become a major, next generation flat panel display configuration.
In a conventional PDP, with reference to FIG. 16, address electrodes 101 are formed along one direction (axis X direction in the drawing) on rear substrate 100. Dielectric layer 103 is formed over an entire surface of rear substrate 100 on which address electrodes 101 are located such that dielectric layer 103 covers address electrodes 101. Barrier ribs 105 are formed on dielectric layer 103 in a striped pattern and at locations corresponding to between address electrodes 101. Formed between barrier ribs 105 are red, green, and blue phosphor layers 107.
Formed on a surface of front substrate 110 facing rear substrate 100 are discharge sustain electrodes 114. Each of the discharge sustain electrodes 114 includes a pair of transparent electrodes 112 and a pair of bus electrodes 113. Transparent electrodes 112 and bus electrodes 113 are arranged in a direction substantially perpendicular to address electrodes 101 of rear substrate 100 (axis Y direction). Dielectric layer 116 is formed over an entire surface of front substrate 110 on which discharge sustain electrodes 114 are formed such that dielectric layer 116 covers discharge sustain electrodes 114. MgO protection layer 118 is formed covering entire dielectric layer 116.
Areas between where address electrodes 101 of rear substrate 100 and discharge sustain electrodes 114 of front substrate 110 intersect become areas that form discharge cells.
An address voltage Va is applied between address electrodes 101 and discharge sustain electrodes 114 to perform address discharge, then a sustain voltage Vs is applied between a pair of the discharge sustain electrodes 114 to perform sustain discharge. Ultraviolet rays generated at this time excite corresponding phosphor layers such that visible light is emitted through transparent front substrate 110 to realize the display of images.
However, with the PDP structure in which discharge sustain electrodes 114 are formed as shown in FIG. 16 and barrier ribs 105 are provided in a striped pattern, crosstalk may occur between adjacent discharge cells (i.e., discharge cells adjacent to one another with barrier ribs 105 provided therebetween). Further, since there is no structure provided between adjacent barrier ribs 105 for dividing the discharge cells, it is possible for mis-discharge to occur between adjacent discharge cells within adjacent barrier ribs 105. To prevent these problems, it is necessary to provide a minimum distance between discharge sustain electrons 114 corresponding to adjacent pixels. However, this limits efforts at improving discharge efficiency.
In an effort to remedy these problems, PDPs having improved electrode and barrier rib structures have been disclosed as shown in FIGS. 17 and 18.
In the PDP structure appearing in FIG. 17, although barrier ribs 121 are formed in the typical striped pattern, discharge sustain electrodes 123 are changed in configuration. That is, discharge sustain electrodes 123 include transparent electrodes 123a and bus electrodes 123b, with a pair of transparent electrodes 123a being formed for each discharge cell in such a manner to extend from bus electrodes 123b and oppose one another. U.S. Pat. No. 5,661,500 discloses a PDP with such a configuration. However, in the PDP structured in this manner, mis-discharge along the direction that barrier ribs 121 are formed remains a problem.
In the PDP structure appearing in FIG. 18, a matrix structure for barrier ribs 125 is realized. In particular, barrier ribs 125 include vertical barrier ribs 125a and horizontal barrier ribs 125b that intersect. Japanese Laid-Open Patent No. Heisei 10-149771 discloses a PDP with such a configuration.
However, with the use of such a matrix barrier rib structure, since all areas except for where the barrier ribs are formed are designed as discharge regions, there come to be present only areas that generate heat and no areas that absorb or disperse heat. As a result, after a certain amount of time has elapsed, temperature differences occur between cells in which discharge occurs and in which discharge does not occur. These temperature differences not only affect discharge characteristics, but also result in differences in brightness, the generation of bright afterimages, and other such quality problems. Bright afterimages refers to a difference in brightness occurring between a localized area and its peripheries even after a pattern of brightness that is greater than its peripheries is displayed for a predetermined time interval then returned to the brightness of the overall screen.
Further, in the PDP having barrier ribs 125 of such a matrix structure, either the phosphor layers are unevenly formed in corner areas that define the discharge cells, or the distance from the phosphor layers to discharge sustain electrodes 127 is significant enough that the efficiency of converting into visible light is reduced.